Occurrence: Worldwide. Mosquitoes are common in areas near still or stagnant water or in damp climates. Species affected: All. Age affected: All.

Causes: Order Diptera includes all flies (species of Culicoides, Simulium, Musca and Fannia) and mosquitoes (Culex and Psorophora spp.).

Effects: Adult flies and mosquitoes are ideal vectors of disease. Can be so numerous as to create a health and public relations concern.